The showy plants that most Americans call "geraniums" are more correctly called "pelargoniums" and are part of the large Geraniaceae family. No matter which name you use, geraniums have a colorful history. Hard and fast definitions are difficult to come by, but "historic" geraniums can be broadly classified as those in existence before World War I.
Historic geraniums are a diverse group. The leaves can be the traditional rounded, lobed shape or so deeply dissected that they are almost fern-like. Some geranium leaves feel rough or hairy to the touch. Plants may have an upright habit; a lax, open growth pattern; or even a trailing habit. Flowers range from small, single, five-petaled blossoms to rounded flowerheads made up of scores of individual flowers with petals of white, all shades of pink, red, red-orange and purple. Petals may also be bi-colored .
Geraniums are native to South Africa and were introduced to Europe in the 18th century. By Victorian times, in the 19th century, geraniums were wildly popular and hybridizers, both amateur and professional, attempted to outdo each other in the development of new varieties. Though interest in geraniums waned between World Wars I and II, the decorative plants returned to popularity in the second half of the 20th century and remain so today.
Historic Varieties--Fancy-Leafed Zonals
Common window box, bedding or container geraniums are usually the "zonal" type, which feature a dark ring on each leaf. Historically, these zonals were sometimes bred for exotic leaf color, with flowers as a secondary attraction. Antique varieties include "Mrs. Cox," with yellow, red and green leaves and pink flowers; and "Dolly Varden," featuring green, butterfly-shaped leaf centers ringed in red and accented with white leaf edges. The single flowers are bright red.
Historic Varieties: Regals
Developed in 19th century English royal greenhouses, regal geraniums have exceptionally large flowerheads. The petals can be frilly and the colors intense and rich. Bi-colored varieties are common. Regals are sometimes call "Martha Washington" geraniums in the United States. Antique varieties include "Black Knight," with maroon petals edged in white, and "Mrs. Hickman," with frilly maroon, pink and white flowers.
These traditional favorites feature leaves with fragrances reminiscent of various fruits, including citrus, spices, mint and rose. The flowers are generally smaller than those of traditional bedding geraniums. Scented geraniums have long been used in cooking, medicine, cosmetics and for sachets and potpourris. Antique varieties include rose-scented "Lady Plymouth" and "Attar of Roses," lemon-scented Pelargonium crispum and orange-scented "Prince of Orange."
Pelargoniums are tender in cold-winter climates and should be brought indoors in the fall. Some, like the regals, are better grown in greenhouses or conservatories than outdoors. Water all geraniums when the soil surrounding the plants is dry to the touch and prune after blooming to assure repeat flowering.